U.S. Pat. No. 5,099,620--Carey--describes a rain gutter cover construction said to offer particular advantage in preventing leaves, twigs and other debris from entering the gutter and stopping rainwater flow into the connected downspouts. One problem existing with such construction, however, was that the narrow slots that were employed themselves easily became clogged--especially when the installation was on a dwelling or building surrounded by pine trees or honey locust trees whose needles and sap tended to clog up the openings; in such situations, it was found necessary to brush those slots clear periodically, sometimes up to three times per year. This, and other problems associated with such construction were overcome, by the use of a rain gutter cover of a new and unique type, described in my pending Application, Ser. No. 07/935,978, filed Aug. 27, 1992, and now U.S. Pat. No. 5,305,562, issued on Apr. 26, 1994.
In considering this matter further, the realization came to mind that the difficulty encountered resulted from a compromise in dimensioning the slots employed to allow rainwater to enter easily, while making it difficult for leaves, twigs, needles and other debris to pass. That is, by having the slots large so as to capture as much rainwater as possible, it became easier for the unwanted debris to enter as well; conversely, by making the slots small enough to keep out as much debris as acceptable, a concomitant decrease in the captured rainwater followed. Some alternative to this would thus be desired--because if the slots were made sufficiently small to keep out the debris, the rainwater which would not be diverted into the trough of the gutter would continue to cascade over the front of the gutter, and would form icicles during the cold weather season.
Investigation showed another need for an improvement in the described construction of U.S. Pat. No. 5,099,620, in that the repeated oscillation of the sheet-metal construction employed under the repeated forces of wind, rain and snow produced a measurable tendency for a weakening of the construction, and, thus, a reasonably expected shortened lifetime.